How do I limit gloss/reflection to only intense sources such as a light source?
As far as I know, there is no way to reflect only Lights/Emission shaders but there is a method to prepare your scene and objects to mimic such effect.

For this example I'm using simple scene with two mesh lights, HDRI lightning and simple objects.

Comparison:



Reflective material:



This is simple 'fake PBR' setting, Layer Weight node will allow you to make reflections be harder/softer.

Other objects and World setup:

You will need to disable Glossy Ray Visibility for every object that you don't won't to be visible in your reflective material. So in this case I have disabled Glossy in Cycles Settings of each object and Ray Visibility > Glossy under World settings to 'mute' HDRI map in reflection.